1. Field of the Invention
The present invention is related to a storage system capable of improving access performance from a host to storage apparatuses, and also related to a method for managing the storage system.
2. Description of the Related Art
In storage systems, the ranges of which are higher than, or equal to a middle range, ports provided on the side of storage apparatuses, whose port numbers have been limited, are commonly shared by a large number of business hosts. As a result, a function capable of being connected to a plurality of business hosts has been provided to one storage apparatus-sided port. Since a storage apparatus discriminates one business host from other business hosts based upon a WWN (World Wide Name) allocated to an HBA (Host Bus Adapter) of the first-mentioned business host, exclusively-used LUs (Logical Units) can be provided to the respective business hosts by a single port thereof.
There is an upper limit number in command numbers (will be referred to as “command multiplex number” hereinafter) which can be simultaneously executed by a single port provided on the side of a storage apparatus. In order that a total number of commands which are simultaneously issued from respective hosts does not exceed the upper limit number of the storage apparatus-sided port, while the respective hosts have been connected to the above-described single port, HBAs of the respective hosts are required to set upper limit values of command multiplex numbers.
On the other hand, JP-A-2005-322181 discloses such a method for controlling access permissions every path on the side of a storage apparatus. In other words, a storage control apparatus (namely, control apparatus provided on the side of storage apparatus) monitors and controls a total value of command multiplex numbers which are set to respective hosts to be connected in order that this total command multiplex number does not exceed command multiplex processing capability of the storage control apparatus. It should be understood that a path implies an I/O (Input/Output) path which connects a host to a storage apparatus.